An image forming method using a light-sensitive material which contains silver halide, a reducing agent and a polymerizable compound is disclosed Japanese Patent Publication No. 45(1970)-11149 (corresponding to U.S. Pat. No. 3,697,275, German Patent No. 1720665 and British Patent No. 131200). The method comprises the steps of imagewise exposing to light the light-sensitive material and developing the material by a developing solution to imagewise harden the polymerizable compound so as to form a polymer image. In the method, the polymerization caused by a radical of an oxidation product of the reducing agent, which is formed by the development of the silver halide.
Further, a light-sensitive material wherein silver halide is separated from a polymerizable compound is disclosed in Japanese Patent Provisional Publication No. 58(1983)-121031 (corresponding to U.S. Pat. No. 4,547,450 and German Patent Provisional Publication No. 3300817A). The light-sensitive material comprises a light-sensitive layer (silver halide photographic emulsion layer) containing the silver halide, a polymerizable layer containing the polymerizable compound and a support.
In the light-sensitive material separately having a light-sensitive layer and a polymerizable layer, it is essential for image formation that the radical of the oxidized reducing agent can be transferred from the light-sensitive layer to the polymerizable layer. As is described in Japanese Patent Provisional Publication No. 58(1983)-121031 (at column 2, lines 46.53 in U.S. Pat. No. 4,547,450), considering the instability of radicals, it is surprising that a radical formed in the light-sensitive layer diffused into another layer to initiate polymerization.
The image forming method disclosed in Japanese Patent Provisional Publication No. 58(1983)-121031 employs a wet development process using a developing solution. Accordingly, the developing solution permeates the light-sensitive layer and the polymerizable layer at the development process. Further, the reducing agents disclosed in the publication are soluble in water. Therefore, the radical of the oxidized reducing agent formed in the light-sensitive layer is transferred to the polymerizable layer with the developing solution. In other words, water contained in the developing solution functions as a medium or carrier of the radical.
On the other hand, another image forming method which employs a dry development process is disclosed in Japanese Patent Publication No. 61(1986)-69062 or No. 61(1986)-73145 (the contents of these two publications are described in U.S. Pat. No. 4,629,676 and European Patent Provisional Publication No. 0174634A). The method comprises imagewise exposing a light-sensitive material and heating the material to imagewise polymerize the polymerizable compound so as to form a polymer image. Further, Japanese Patent Provisional Publication No. 64(1989)-17047 (corresponding to U.S. patent application Ser. No. 07/217,207 now allowed) discloses a light-sensitive material which is heat-developable and is advantageously used in preparation of a printing plate.
The dry development process is conducted under the conditions substantially not containing water. There is no water, which functions as a medium or carrier of the radical of the oxidized reducing agent in the image forming method disclosed in Japanese Patent Provisional Publication No. 58(1983)-121031. Accordingly, it has been considered that the separation of a light-sensitive layer and a polymerizable layer is difficult in an image forming method employing a dry development process. In fact, a light-sensitive material separately having the light-sensitive layer and the polymerizable layer has been scarcely proposed in the method employing the dry development process
In the dry and heat development process, the applicant has noted that a reducing agent itself can be transferred between two layers. Therefore, the applicant has proposed a light-sensitive material wherein silver halide is separated from a polymerizable compound so long as the reducing agent itself functions as a polymerization inhibitor in an image forming method, as is disclosed in FIG. 2 of Japanese Patent Provisional Publication No. 61(1986)-75342 (which corresponds to FIG. 2 of U.S. Pat. No. 4,649,098). The light-sensitive material disclosed in the publication comprises a support having provided thereon a light-sensitive layer containing silver halide and a reducing agent, and a photopolymerizable layer containing a polymerizable compound and a photopolymerization initiator.
But, the radical of the oxidized reducing agent is much less stable than the reducing agent itself as is described in Japanese Patent Provisional Publication No. 58(1983)-121031. Accordingly, it has not yet been considered nor tried at all to transfer the radical by heat between two layers.